在vb中实现鼠标手势

1.什么是鼠标手势:
我的理解,按着鼠标某键(一般是右键)移动鼠标,然后放开某键,程序会识别你的移动轨迹,做出相应的响应.

2.实现原理:
首先说明一下,我在网上没有找到相关的文档,我的方法未必与其他人是一致的,实际效果感觉还可以.
鼠标移动的轨迹我们可以将其看成是许多小段直线组成的,然后这些直线的方向就是鼠标在这段轨迹中的方向了.
3.实现代码:
还要说明一下,
a)要捕获鼠标的移动事件,可以使用vb中的mousemove事件,但这个会受到一些限制(例如,在webbrowser控件上就没有这个事件).于是这个例子中,我用win api,在程序中安装个鼠标钩子,这样就能够捕获整个程序的鼠标事件了.
b)这个里只是个能捕获鼠标向上,下,左,右的移动的例子.(呵呵,其实这四方向一般也足够了:))

新建Standrad EXE,添加一个Module

form1的代码如下

Option Explicit

Private Sub Form_Load()
Call InstallMouseHook
End Sub


Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Call UninstallMouseHook
End Sub


Module1的代码如下

Option Explicit

Public Const HTCLIENT As Long = 1

Private hMouseHook As Long
Private Const KF_UP As Long = &H80000000

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, hpvSource As Any, ByVal cbCopy As Long)

Private Type POINTAPI
X As Long
Y As Long

End Type

Public Type MOUSEHOOKSTRUCT
pt As POINTAPI
hwnd As Long
wHitTestCode As Long
dwExtraInfo As Long

End Type

Public Declare Function CallNextHookEx Lib "user32" _
(ByVal hHook As Long, _
ByVal ncode As Long, _
ByVal wParam As Long, _
ByVal lParam As Long) As Long
Public Declare Function SetWindowsHookEx Lib "user32" _
Alias "SetWindowsHookExA" _
(ByVal idHook As Long, _
ByVal lpfn As Long, _
ByVal hmod As Long, _
ByVal dwThreadId As Long) As Long
Public Declare Function UnhookWindowsHookEx Lib "user32" _
(ByVal hHook As Long) As Long

Public Const WH_KEYBOARD As Long = 2
Public Const WH_MOUSE As Long = 7

Public Const HC_SYSMODALOFF = 5
Public Const HC_SYSMODALON = 4
Public Const HC_SKIP = 2
Public Const HC_GETNEXT = 1
Public Const HC_ACTION = 0
Public Const HC_NOREMOVE As Long = 3

Public Const WM_LBUTTONDBLCLK As Long = &H203
Public Const WM_LBUTTONDOWN As Long = &H201
Public Const WM_LBUTTONUP As Long = &H202
Public Const WM_MBUTTONDBLCLK As Long = &H209
Public Const WM_MBUTTONDOWN As Long = &H207
Public Const WM_MBUTTONUP As Long = &H208
Public Const WM_RBUTTONDBLCLK As Long = &H206
Public Const WM_RBUTTONDOWN As Long = &H204
Public Const WM_RBUTTONUP As Long = &H205
Public Const WM_MOUSEMOVE As Long = &H200
Public Const WM_MOUSEWHEEL As Long = &H20A


Public Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Const MK_RBUTTON As Long = &H2
Public Declare Function ScreenToClient Lib "user32" (ByVal hwnd As Long, lpPoint As POINTAPI) As Long


Public Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Public Const VK_LBUTTON As Long = &H1
Public Const VK_RBUTTON As Long = &H2
Public Const VK_MBUTTON As Long = &H4

Dim mPt As POINTAPI
Const ptGap As Single = 5 * 5
Dim preDir As Long
Dim mouseEventDsp As String
Dim eventLength As Long

'######### mouse hook #############

Public Sub InstallMouseHook()
hMouseHook = SetWindowsHookEx(WH_MOUSE, AddressOf MouseHookProc, _
App.hInstance, App.ThreadID)
End Sub

Public Function MouseHoo